摘要
目的 :探讨内毒素 (脂多糖 ,LPS)诱导肺泡Ⅱ型上皮细胞 (AECⅡ )凋亡的分子机制 ,LPS介导的AECⅡ凋亡是否需要肿瘤坏死因子 α(TNF α)的参与。 方法 :采用文献方法加以修改而建立小鼠 (C5 7、TNFKO)AECⅡ体外培养模型 ,采用LPS和重组小鼠TNF α刺激细胞 2 4h后观察。用ELISA法测定细胞培养上清中TNF α水平 ,而细胞凋亡检测采用TNUEL法。 结果 :①LPS诱导AECⅡ细胞凋亡在C5 7野生型小鼠呈剂量依赖关系 ,LPS 5 0 μg/ml刺激时 ,细胞凋亡率为 (2 2 .7± 2 .1 ) % ,对照组为 (6 .4± 0 .9) % ,P <0 .0 5 ;②LPS在诱导AECⅡ凋亡的同时 ,诱导TNF α水平升高 1 1倍 ;③大剂量的重组TNF α并不能明显诱导AECⅡ凋亡 ;④在TNF基因剔除 (knockout,KO)小鼠 ,LPS仍可明显诱导AECⅡ凋亡。 结论 :①在体外培养条件下 ,LPS可明显诱导AECⅡ凋亡 ;②LPS刺激的TNF α释放并不参与LPS介导的AECⅡ凋亡 ;③LPS诱导的AECⅡ凋亡是通过TNF
Objectives:To examine whether lipopolysaccharide (LPS) induced apoptosis correlates with TNF α release by type Ⅱ alveolar epithelial cells (AEC Ⅱ), whether TNF α knockout (TNF KO) abrogates the induction of apoptosis by LPS and whether TNF α is sufficient to induce apoptosis in this cell type. Methods:AEC Ⅱ was isolated from wild type mice and TNF KO mice. Cells were stimulated with LPS or recombinant murine TNF α for 24 h. TNF α in culture supernatant was determined by ELISA following LPS stimulation. Apoptosis was determined by the TUNEL assay after treatment with either LPS or TNF α. Results:LPS induced apoptosis in wild type AEC Ⅱ in a concentration dependent manner. LPS induced AEC Ⅱ apoptosis was accompanied by a 11 fold increase from (0.073±0.065) ng/ml in controls to( 0.94±0.14)ng/ml in 50 μg/ml of LPS( P <0.01) in TNF α release. However, increasing concentration (5 ng or 25)ng/ml of recombinant murine TNF α failed to induce AEC Ⅱ apoptosis. In addition, apoptosis did occur in AEC Ⅱ isolated from TNF KO mice following LPS stimulation. Conclusions:This study confirms that LPS induces TNF α release and apoptosis in murine AEC Ⅱ in vitro. Exogenous TNF α failed to induce AEC Ⅱ apoptosis, and apoptosis occurred following LPS stimulation in cells lacking the ability to produce TNF α. Taken together, these results suggest that LPS induced AEC Ⅱ apoptosis occurs by a TNF α independent mechanism.
出处
《医学研究生学报》
CAS
2003年第6期420-423,共4页
Journal of Medical Postgraduates
